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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        // let a = 10
        // let b =  function(){
        //     console.log('666');
            
        // }
        // b()

       //逻辑中断 
    //    function fn (a,b){
    //     a = a || 1
    //     b = b || 1
    //     console.log(a + b);
        
    //    }
    //    fn ()
    </script>
</body>
</html>